Fission Tracks in Zircons: Evidence for Abundant Nuclear Decay

by
Andrew A. Snelling, Ph.D.

RATE II: Radioisotopes and the Age of The Earth: Results of a Young-Earth Creationist Research Initiative, (Volume II), L. Vardiman et al., eds. (San Diego, CA: Institute for Creation Research and the Creation Research Society, 2005)

Abstract

Fission tracks are a physical record of in situ nuclear decay, their density being directly proportional to the amount of nuclear decay
that has occurred. The aim of this study was to investigate whether the amounts of fission tracks in zircon grains in targeted rock units (that is, their fission track “ages”) matched the radioisotope “ages” of those rocks. Stratigraphically well-constrained volcanic ash or tuff beds located in the Grand Canyon-Colorado Plateau “type section” of the Flood strata record were chosen—the Cambrian Muav and Tapeats tuffs from the western Grand Canyon (early Flood), Jurassic Morrison Formation tuff beds, southeastern Utah (middle Flood), and the Miocene Peach Springs Tuff, southeastern California and western Arizona (late Flood or post-Flood). The fission track “ages” of zircon grains separated from samples of these tuff units were determined by a specialized professional laboratory using the external detector method and a zeta (ζ) calibration factor. The observed fission track densities measured in all the zircons (and thus the fission track “ages”) from the samples of the Jurassic and Miocene tuffs, and in some of the zircons from the Muav and Tapeats tuffs, were found to exactly equate to the quantities of nuclear decay measured by radioisotope determinations of the same rock units. Though thermal annealing of fission tracks had occurred in some zircon grains in the two Cambrian Grand Canyon tuffs, the U-Pb radioisotope system had also been thermally reset, the resulting reset ages in both instances coinciding with the onset of the Laramide uplift of the Colorado Plateau. The fact that the thermal annealing of the fission tracks and the thermal resetting of the U-Pb radioisotope system in those zircon grains were exactly parallel is unequivocal confirmation that the radioisotope ratios are a product of radioactive decay, in just the same way as the fission tracks are physical evidence of nuclear decay. Furthermore, because the resetting of the U-Pb radioisotope system in zircons will only occur at elevated temperatures, the fact that it has been reset in these zircons could therefore be due to them having been heated by accelerated nuclear decay. Even so, in spite of this thermal annealing and resetting, there remains sufficient strong evidence to conclude that both the fission tracks and radioisotope ratios in the zircons in the Cambrian Grand Canyon tuff beds record more than 500 million years worth (at today’s rates) of nuclear and radioisotope decay during deposition of the Phanerozoic strata sequence of the Grand Canyon-Colorado Plateau region. Given the independent evidence that most of this strata sequence was deposited catastrophically during the year-long global Flood about 4500 years ago, then 500 million or more years worth (at today’s rates) of nuclear and radioisotope decay had to have occurred during the Flood year about 4500 years ago. Thus, the fission tracks in the zircons in these tuffs are physical evidence of accelerated nuclear decay.